from then on与since than在用法上有什么区别

题目

from then on与since than在用法上有什么区别
哪个该用现完,哪个该用过去时?
辅导书上有句：From then on,nobody has caught that disease.
Frome then on,they lived together happily.
是不是两种都可以?

答案

since than用现完
from then on过去时,现完都可以
只要有since就用完成时